[Living longer than expected: admitted to a hospice with an underestimated life expectancy]. / Langer leven dan voorspeld.

In the Netherlands, patients who have a life expectancy of less than three months may be admitted to a hospice. In a small number of patients, however, their life expectancy is underestimated. It is assumed that patients are delighted to have this extra time. We present the cases of three patients admitted to a large Dutch hospice: two females aged 82 and 83 years, and a 49-year-old man -who ended up living (significantly) longer than expected. Their cases make clear that patients in this situation may suffer from psychological, psychosocial, and existential distress. We argue that it is important that patients and their relatives are informed about their life expectancy, but that uncertainty in the estimation of said expectancy should be emphasized.

De novo and inherited mutations in the X-linked gene CLCN4 are associated with syndromic intellectual disability and behavior and seizure disorders in males and females.

Variants in CLCN4, which encodes the chloride/hydrogen ion exchanger CIC-4 prominently expressed in brain, were recently described to cause X-linked intellectual disability and epilepsy. We present detailed phenotypic information on 52 individuals from 16 families with CLCN4-related disorder: 5 affected females and 2 affected males with a de novo variant in CLCN4 (6 individuals previously unreported) and 27 affected males, 3 affected females and 15 asymptomatic female carriers from 9 families with inherited CLCN4 variants (4 families previously unreported). Intellectual disability ranged from borderline to profound. Behavioral and psychiatric disorders were common in both child- and adulthood, and included autistic features, mood disorders, obsessive-compulsive behaviors and hetero- and autoaggression. Epilepsy was common, with severity ranging from epileptic encephalopathy to well-controlled seizures. Several affected individuals showed white matter changes on cerebral neuroimaging and progressive neurological symptoms, including movement disorders and spasticity. Heterozygous females can be as severely affected as males. The variability of symptoms in females is not correlated with the X inactivation pattern studied in their blood. The mutation spectrum includes frameshift, missense and splice site variants and one single-exon deletion. All missense variants were predicted to affect CLCN4's function based on in silico tools and either segregated with the phenotype in the family or were de novo. Pathogenicity of all previously unreported missense variants was further supported by electrophysiological studies in Xenopus laevis oocytes. We compare CLCN4-related disorder with conditions related to dysfunction of other members of the CLC family.

Pharmacokinetic considerations and recommendations in palliative care, with focus on morphine, midazolam and haloperidol.

INTRODUCTION: A variety of medications are used for symptom control in palliative care, such as morphine, midazolam and haloperidol. The pharmacokinetics of these drugs may be altered in these patients as a result of physiological changes that occur at the end stage of life. AREAS COVERED: This review gives an overview of how the pharmacokinetics in terminally ill patients may differ from the average population and discusses the effect of terminal illness on each of the four pharmacokinetic processes absorption, distribution, metabolism, and elimination. Specific considerations are also given for three commonly prescribed drugs in palliative care: morphine, midazolam and haloperidol). EXPERT OPINION: The pharmacokinetics of drugs in terminally ill patients can be complex and limited evidence exists on guided drug use in this population. To improve the quality of life of these patients, more knowledge and more pharmacokinetic/pharmacodynamics studies in terminally ill patients are needed to develop individualised dosing guidelines. Until then knowledge of pharmacokinetics and the physiological changes that occur in the final days of life can provide a base for dosing adjustments that will improve the quality of life of terminally ill patients. As the interaction of drugs with the physiology of dying is complex, pharmacological treatment is probably best assessed in a multi-disciplinary setting and the advice of a pharmacist, or clinical pharmacologist, is highly recommended.

Altered neuronal network and rescue in a human MECP2 duplication model.

Increased dosage of methyl-CpG-binding protein-2 (MeCP2) results in a dramatic neurodevelopmental phenotype with onset at birth. We generated induced pluripotent stem cells (iPSCs) from patients with the MECP2 duplication syndrome (MECP2dup), carrying different duplication sizes, to study the impact of increased MeCP2 dosage in human neurons. We show that cortical neurons derived from these different MECP2dup iPSC lines have increased synaptogenesis and dendritic complexity. In addition, using multi-electrodes arrays, we show that neuronal network synchronization was altered in MECP2dup-derived neurons. Given MeCP2 functions at the epigenetic level, we tested whether these alterations were reversible using a library of compounds with defined activity on epigenetic pathways. One histone deacetylase inhibitor, NCH-51, was validated as a potential clinical candidate. Interestingly, this compound has never been considered before as a therapeutic alternative for neurological disorders. Our model recapitulates early stages of the human MECP2 duplication syndrome and represents a promising cellular tool to facilitate therapeutic drug screening for severe neurodevelopmental disorders.

X-exome sequencing of 405 unresolved families identifies seven novel intellectual disability genes.

X-linked intellectual disability (XLID) is a clinically and genetically heterogeneous disorder. During the past two decades in excess of 100 X-chromosome ID genes have been identified. Yet, a large number of families mapping to the X-chromosome remained unresolved suggesting that more XLID genes or loci are yet to be identified. Here, we have investigated 405 unresolved families with XLID. We employed massively parallel sequencing of all X-chromosome exons in the index males. The majority of these males were previously tested negative for copy number variations and for mutations in a subset of known XLID genes by Sanger sequencing. In total, 745 X-chromosomal genes were screened. After stringent filtering, a total of 1297 non-recurrent exonic variants remained for prioritization. Co-segregation analysis of potential clinically relevant changes revealed that 80 families (20%) carried pathogenic variants in established XLID genes. In 19 families, we detected likely causative protein truncating and missense variants in 7 novel and validated XLID genes (CLCN4, CNKSR2, FRMPD4, KLHL15, LAS1L, RLIM and USP27X) and potentially deleterious variants in 2 novel candidate XLID genes (CDK16 and TAF1). We show that the CLCN4 and CNKSR2 variants impair protein functions as indicated by electrophysiological studies and altered differentiation of cultured primary neurons from Clcn4(-/-) mice or after mRNA knock-down. The newly identified and candidate XLID proteins belong to pathways and networks with established roles in cognitive function and intellectual disability in particular. We suggest that systematic sequencing of all X-chromosomal genes in a cohort of patients with genetic evidence for X-chromosome locus involvement may resolve up to 58% of Fragile X-negative cases.

Clinical implementation of NIPT - technical and biological challenges.

Non-invasive prenatal testing (NIPT) for fetal aneuploidy detection is increasingly being offered in the clinical setting. Whereas the majority of tests only report fetal trisomies 21, 18 and 13, genome-wide analyses have the potential to detect other fetal, as well as maternal, aneuploidies. In this review, we discuss the technical and clinical advantages and challenges associated with genome-wide cell-free fetal DNA profiling.

The communication of secondary variants: interviews with parents whose children have undergone array-CGH testing.

Children with unexplained developmental disabilities or congenital anomalies are increasingly being referred for genetic diagnostic testing using array-comparative genomic hybridisation (array-CGH) and next-generation sequencing (NGS) technologies. Their parents will have to deal with the secondary variants that will inevitably arise. We conducted 16 prospective semi-structured interviews with native Dutch-speaking parents whose children had undergone clinical array-CGH testing. The interviews explored the parents' experiences, expectations and opinions, specifically regarding the communication of results. Concrete examples of 'unexpected results' were provided to help guide the discussion, differing in severity, treatability, time of onset, level of risk, and carrier status. Data was analysed using content and narrative analysis methodologies. Parental motivations for and against the disclosure of unexpected results cluster around four main themes: actionability; knowledge; context; and characteristics of the result. Most parents wished to know all types of results. Disclosure was framed within a holistic, contextual, family-wide view. Genetic counselling should aim to integrate explorations of the motivations of parents surrounding the disclosure of results with good clinical care.

Microduplication 22q11.2: a description of the clinical, developmental and behavioral characteristics during childhood.

Microduplication 22q11.2 is a recently discovered genomic disorder. So far, targeted research on the cognitive and behavioral characteristics of individuals with this microduplication is limited. Therefore, 11 Flemish children (3-13 years old) with a microduplication 22q 1.2 were investigated in order to describe their clinical, developmental and behavioral characteristics. We measured their general intelligence, visual-motor capacities, attention, behavioral problems and characteristics of autism. In addition, there was an interview with the parents on developmental history and we reviewed available information from other specialists. The results show that the cognitive and behavioral phenotype of the children with microduplication 22q.11.2 is very wide and heterogeneous. Some of the children have a cognitively nearly normal development whereas others are more severely affected. All children had some degree of developmental delay and some of them have an intellectual disability. The most common clinical features include congenital malformations such as heart defects and cleft lip, feeding problems, hearing impairment and facial dysmorphism. The most common non-medical problems are learning difficulties, motor impairment, attention deficits, social problems and behavioral problems. There is no correlation between the size of the duplication and the phenotype.

Neuropsychopathology in 7 Patients with the 22q13 Deletion Syndrome: Presence of Bipolar Disorder and Progressive Loss of Skills.

The 22q13 deletion syndrome is characterised by intellectual disability (ID), delayed or absent speech, autistic-like behaviour and minor, nonspecific dysmorphic features. The deletion of the SHANK3 gene is thought to be responsible for these features. In this study, the clinical data of 7 patients with the 22q13 deletion syndrome are presented, obtained by clinical genetic examination, direct behavioural observation and by interview of family members and/or caregivers, complemented by behavioural questionnaires. The specific focus was on behaviour, psychopathology and the level of functioning during life course in order to determine common features that might contribute to the delineation of the syndrome. Major findings were a high incidence of psychiatric disorders, more in particular bipolar disorder (BPD) and attention deficit hyperactivity disorder (ADHD), and a sudden deterioration after acute events, in addition to a progressive loss of skills over years. Therefore, a deletion of SHANK3 may result in a dysfunctional nervous system, more susceptible to developmental problems and psychiatric disorders on the one hand, less able to recuperate after psychiatric and somatic events, and more vulnerable to degeneration at long term on the other hand. These results are exploratory and need to be confirmed in a larger sample.

Sporadic male patients with intellectual disability: contribution of X-chromosome copy number variants.

Genome-wide array comparative genome hybridization has become the first in line diagnostic tool in the clinical work-up of patients presenting with intellectual disability. As a result, chromosome X-copy number variations are frequently being detected in routine diagnostics. We retrospectively reviewed genome wide array-CGH data in order to determine the frequency and nature of chromosome X-copy number variations (X-CNV) in a cohort of 2222 sporadic male patients with intellectual disability (ID) referred to us for diagnosis. In this cohort, 68 males were found to have at least one X-CNV (3.1%). However, correct interpretation of causality remains a challenging task, and is essential for proper counseling, especially when the CNV is inherited. On the basis of these data, earlier experience and literature data we designed and propose an algorithm that can be used to evaluate the clinical relevance of X-CNVs detected in sporadic male ID patients. Applied to our cohort, 19 male ID patients (0.85%) were found to carry a (likely) pathogenic X-CNV.

MECP2 Duplication Syndrome.

Since the initial report that clearly established a causal role between duplication of the MECP2 gene and a severe syndromic form of intellectual disability, many new patients have been identified and reported, and the etiology in already published families solved. This has led to the establishment of a clinically recognizable disorder. Here, we review the clinical data of 129 reported and nonreported male patients with MECP2 duplication syndrome.

A balanced translocation t(6;14)(q25.3;q13.2) leading to reciprocal fusion transcripts in a patient with intellectual disability and agenesis of corpus callosum.

We identified a male patient presenting with intellectual disability and agenesis of the corpus callosum, carrying an apparently balanced, reciprocal, de novo translocation t(6;14)(q25.3;q13.2). Breakpoint mapping, using array painting, identified 2 interesting candidate genes, ARID1B and MRPP3, disrupted in the patient. Unexpectedly, the rearrangement produced 3 in-frame reciprocal fusion transcripts that were further characterized. Formation of fusion transcripts is mainly reported in acquired malignancies and is very rarely observed in patients with intellectual disability (ID) and/or multiple congenital malformations (MCA). Additional experimental results suggest that ARID1B, a gene involved in chromatin remodeling, constitutes a good candidate for the central nervous system phenotype present in the patient.

Refining the phenotype associated with MEF2C haploinsufficiency.

Recently, submicroscopic deletions of the 5q14.3 region have been described in patients with severe mental retardation (MR), stereotypic movements, epilepsy and cerebral malformations. Further delineation of a critical region of overlap in these patients pointed to MEF2C as the responsible gene. This finding was further reinforced by the identification of a nonsense mutation in a patient with a similar phenotype. In brain, MEF2C is essential for early neurogenesis, neuronal migration and differentiation. Here we present two additional patients with severe MR, autism spectrum disorder and epilepsy, carrying a very small deletion encompassing the MEF2C gene. This finding strengthens the role of this gene in severe MR, and enables further delineation of the clinical phenotype.

Mutations of the UPF3B gene, which encodes a protein widely expressed in neurons, are associated with nonspecific mental retardation with or without autism.

Mutations in the UPF3B gene, which encodes a protein involved in nonsense-mediated mRNA decay, have recently been described in four families with specific (Lujan-Fryns and FG syndromes), nonspecific X-linked mental retardation (XLMR) and autism. To further elucidate the contribution of UPF3B to mental retardation (MR), we screened its coding sequence in 397 families collected by the EuroMRX consortium. We identified one nonsense mutation, c.1081C>T/p.Arg361(*), in a family with nonspecific MR (MRX62) and two amino-acid substitutions in two other, unrelated families with MR and/or autism (c.1136G>A/p.Arg379His and c.1103G>A/p.Arg368Gln). Functional studies using lymphoblastoid cell lines from affected patients revealed that c.1081C>T mutation resulted in UPF3B mRNA degradation and consequent absence of the UPF3B protein. We also studied the subcellular localization of the wild-type and mutated UPF3B proteins in mouse primary hippocampal neurons. We did not detect any obvious difference in the localization between the wild-type UPF3B and the proteins carrying the two missense changes identified. However, we show that UPF3B is widely expressed in neurons and also presents in dendritic spines, which are essential structures for proper neurotransmission and thus learning and memory processes. Our results demonstrate that in addition to Lujan-Fryns and FG syndromes, UPF3B protein truncation mutations can cause also nonspecific XLMR. We also identify comorbidity of MR and autism in another family with UPF3B mutation. The neuronal localization pattern of the UPF3B protein and its function in mRNA surveillance suggests a potential function in the regulation of the expression and degradation of various mRNAs present at the synapse.

Novel PORCN mutations in focal dermal hypoplasia.

Focal dermal hypoplasia (FDH), Goltz or Goltz-Gorlin syndrome, is an X-linked dominant multisystem disorder characterized primarily by involvement of the skin, skeletal system and eyes. We screened for mutations in the PORCN gene in eight patients of Belgian and Finnish origin with firm clinical suspicion of FDH. First, we performed quantitative PCR (qPCR) analysis to define the copy number at this locus. Next, we sequenced the coding regions and flanking intronic sequences of the PORCN gene. Three de novo mutations were identified in our patients with FDH: a 150-kb deletion removing six genes including PORCN, as defined by qPCR and X-array-CGH, and two heterozygous missense mutations; c.992T>G (p.L331R) in exon 11 and c.1094G>A (p.R365Q) in exon 13 of the gene. Both point mutations changed highly conserved amino acids and were not found in 300 control X chromosomes. The three patients in whom mutations were identified all present with characteristic dermal findings together with limb manifestations, which were not seen in our mutation-negative patients. The clinical characteristics of our patients with PORCN mutations were compared with the previously reported mutation-positive cases. In this report, we summarize the literature on PORCN mutations and associated phenotypes.

Refinement of cortical dysgeneses spectrum associated with TUBA1A mutations.

OBJECTIVE: We have recently shown that de novo mutations in the TUBA1A gene are responsible for a wide spectrum of neuronal migration disorders. To better define the range of these abnormalities, we searched for additional mutations in a cohort of 100 patients with lissencephaly spectrum for whom no mutation was identified in DCX, LIS1 and ARX genes and compared these data to five previously described patients with TUBA1A mutations. RESULTS: We detected de novo TUBA1A mutations in six patients and highlight the existence of a prominent form of TUBA1A related lissencephaly. In four patients, the mutations identified, c.1190T>C (p.L397P), c.1265G>A (p.R422H), c.1264C>T (p.R422C), c.1306G>T (p.G436R), have not been reported before and in two others, the mutation corresponds to a recurrent missense mutation, c.790C>T (p.R264C), likely to be a hot spot of mutation. All together, it emerges that the TUBA1A related lissencephaly spectrum ranges from perisylvian pachygyria, in the less severe form, to posteriorly predominant pachygyria in the most severe, associated with dysgenesis of the anterior limb of the internal capsule and mild to severe cerebellar hypoplasia. When compared with a large series of lissencephaly of other origins (ILS17, ILSX or unknown origin), these features appear to be specific to TUBA1A related lissencephaly. In addition, TUBA1A mutated patients share a common clinical phenotype that consists of congenital microcephaly, mental retardation and diplegia/tetraplegia. CONCLUSIONS: Our data highlight the presence of consistent and specific abnormalities that should allow the differentiation of TUBA1A related lissencephalies from those related to LIS1, DCX and ARX genes.

[Heridity of non-syndromal orofacial clefts]. / Erfelijkheid van niet-syndromale orofaciale schisis.

Non-syndromal orofacial clefts are congenital anomalies with a high incidence of heterogeneous origin. The condition is usually multifactorially determined, caused by interaction between multiple genetic and environmental factors. So far, only a few causal factors have been identified. Even in genetically identical individuals like monozygotic twins, the orofacial cleft is usually not fully concordant. As an illustration of non-syndromal orofacial clefts, monozygotic twin brothers with orofacial clefts which are not fully concordant are presented.

Detection and validation of copy number variation in X-linked mental retardation.

Studies to identify the genetic defects associated with X-linked mental retardation (XLMR) in males have revealed tens of genes important for normal brain development and cognitive functioning in men. Despite extensive efforts in breakpoint cloning of chromosomal rearrangements and mutation screening of candidate genes on the X chromosome, still many XLMR families and sporadic cases remain unsolved. It is now clear that submicroscopic copy number changes on the X chromosome can explain about 5% of these idiopathic cases. Interestingly, beside gene deletions, an increase in gene dosage due to genomic duplications seems to contribute to causality more often than expected. Since larger duplications on the X chromosome are tolerated compared to deletions, they often harbour more than one gene hampering the identification of the causal gene. In contrast to copy number variations (CNVs) on autosomes, most disease-associated CNVs on the X chromosome in males are inherited from their mothers who normally do not present with any clinical symptoms due to non-random X inactivation. Here, we review the different methods applied to study copy number alterations on the X chromosome in patients with cognitive impairment, discuss those CNVs that are associated with disease and elaborate on the genes and mechanisms involved. At the end, we will resume in vivo assays to study the relation of CNVs on the X chromosome and mental disability.

Severe visual impairment and retinal changes in a boy with a deletion of the gene for Nance-Horan syndrome.

We present the ophthalmologic findings in a boy with a deletion of Xp22 comprising the gene for Nance-Horan syndrome. Different mechanisms underlying the visual impairment in Nance-Horan syndrome are discussed.

Cryptic deletions are a common finding in "balanced" reciprocal and complex chromosome rearrangements: a study of 59 patients.

Using array comparative genome hybridisation (CGH) 41 de novo reciprocal translocations and 18 de novo complex chromosome rearrangements (CCRs) were screened. All cases had been interpreted as "balanced" by conventional cytogenetics. In all, 27 cases of reciprocal translocations were detected in patients with an abnormal phenotype, and after array CGH analysis, 11 were found to be unbalanced. Thus 40% (11 of 27) of patients with a "chromosomal phenotype" and an apparently balanced translocation were in fact unbalanced, and 18% (5 of 27) of the reciprocal translocations were instead complex rearrangements with >3 breakpoints. Fourteen fetuses with de novo, apparently balanced translocations, all but two with normal ultrasound findings, were also analysed and all were found to be normal using array CGH. Thirteen CCRs were detected in patients with abnormal phenotypes, two in women who had experienced repeated spontaneous abortions and three in fetuses. Sixteen patients were found to have unbalanced mutations, with up to 4 deletions. These results suggest that genome-wide array CGH may be advisable in all carriers of "balanced" CCRs. The parental origin of the deletions was investigated in 5 reciprocal translocations and 11 CCRs; all were found to be paternal. Using customized platforms in seven cases of CCRs, the deletion breakpoints were narrowed down to regions of a few hundred base pairs in length. No susceptibility motifs were associated with the imbalances. These results show that the phenotypic abnormalities of apparently balanced de novo CCRs are mainly due to cryptic deletions and that spermatogenesis is more prone to generate multiple chaotic chromosome imbalances and reciprocal translocations than oogenesis.